Refrigerant exchange arrangement

ABSTRACT

A refrigerant exchange arrangement is claimed with a first oil-trapping chamber ( 10 ) and a second oil-trapping chamber ( 11 ). A refrigerant exchange arrangement of simple construction is to be realised. For this purpose, the second oil-trapping chamber ( 11 ) is disposed within the first oil trapping chamber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of and incorporates byreference essential subject matter disclosed in International PatentApplication No. PCT/DK2007/000318 filed on Jun. 28, 2007 and GermanPatent Application No. 10 2006 030 698.8 filed Jun. 30, 2006.

TECHNICAL FIELD

The invention concerns a refrigerant exchange arrangement with a firstoil-trapping chamber and a second oil-trapping chamber.

BACKGROUND OF THE INVENTION

In the following, the invention is described in connection with theexchange of a refrigerant in the air-conditioning system of a vehicle.However, it can also be used in applications, in which similar problemsoccur.

When servicing the air-conditioning system of a vehicle, it is in manycases necessary to exchange the refrigerant. The term “exchange” doesnot necessarily mean that the refrigerant contained in theair-conditioning system is completely replaced by a new refrigerant. Inmany cases, it will be sufficient to dewater the refrigerant and/or toreplace the oil contained in the refrigerant by new oil. Further, duringsuch a servicing, it should be tested, if any parts of theair-conditioning system should be replaced and if the air-conditioningsystem is tight.

When the refrigerant is removed from the air-conditioning system, it isfirstly required to remove the oil from the refrigerant. This is thecase, irrespective if the refrigerant will subsequently be returned intothe air-conditioning system or used in a different way. In order to trapthe oil, the refrigerant with the oil is led into the first oil-trappingchamber. Here, the flow of the mixture of refrigerant and oil is sloweddown, so that the oil precipitates from the refrigerant. The oil is thenat the bottom of the first oil-trapping chamber. If then the firstoil-trapping chamber is heated, the refrigerant can be evaporated,because it has a lower boiling point than the oil. The refrigerant gasis then led across a filter drier, which removes water from therefrigerant gas. After that the refrigerant gas is compressed by acompressor. In the compressor the refrigerant gas will again get intouch with oil, which is then removed from the refrigerant gas in thesecond oil-trapping chamber. This compressor oil is led to thecompressor again, and the refrigerant gas from the second oil-trappingchamber is led via a condenser, and in many cases also a further filterdrier, to a collector.

The use of two oil-trapping chambers makes the design of such arefrigerant exchange arrangement complicated. As from time to time therefrigerant exchange arrangement must also be serviced, it has to bedetachable and a reassembly also has to be possible. For this purpose,various parts have to be connected to each other and sealed in relationto each other.

BRIEF SUMMARY OF THE INVENTION

The invention is based on the task of providing a refrigerant exchangearrangement with a simple design.

With a refrigerant exchange arrangement, this task is solved in that thesecond oil-trapping chamber is located inside the first oil-trappingchamber.

Thus, it is only necessary to seal the outer, that is, the firstoil-trapping chamber in relation to the environment. Accordingly, onlyone sealing is required, namely towards the outside. A correspondingsealing between the two oil-trapping chambers is not required. Ifrefrigerant or oil should penetrate from one oil-trapping chamber to theother, this is not critical. As a smaller number of parts is required,the manufacturing is more cost-effective. As only one chamber has to besealed towards the outside, the leakage risk is reduced.

Preferably, a gas path out of the second oil-trapping chamber is limitedby a wall of the first oil-trapping chamber. Due to the previouslyoccurring compression, the refrigerant supplied to the secondoil-trapping chamber is at a higher temperature. Now, this highertemperature can be used to heat the first oil-trapping chamber. In orderto realise the most direct possible heat transition from the secondoil-trapping chamber to the first oil-trapping chamber, the gas isguided along the wall of the first oil-trapping chamber. This has twoadvantages. Firstly, the heated refrigerant gas is cooled in the secondoil-trapping chamber after the precipitation of the oil. Secondly, theheat is not lost, but can be used to heat the first oil-trappingchamber.

It is preferred that an insert is arranged in the second oil-trappingchamber, which limits the gas path together with the wall of the firstoil-trapping chamber. By means of the insert, the path along the wall ofthe first oil-trapping chamber can be specified relatively exactly. Aninsert is easy to make and to insert into the second oil-trappingchamber. This keeps the manufacturing costs low. In connection withservicing, the insert can be removed from the second oil-trappingchamber and cleaned. This reduces the risk of the gas path eventuallyblinding. When the insert has been removed from the second oil-trappingchamber, the gas path is accessible from the outside, as the wall of thefirst oil-trapping chamber is missing as cover.

Preferably, the outside of the insert has at least one spirally shapedgroove. Thus, the spirally shaped groove surrounds the insert with asmall pitch. This results in a relatively long length of the gas pathand thus a sufficient time for the heated refrigerant gas to transferits heat to the first oil-trapping chamber.

Preferably, the insert is made of a plastic material. A plastic materialcan easily be shaped to the desired form. Usually it is also easy toclean, so that the servicing is facilitated.

Preferably, at least one outer wall of the first oil-trapping chamber ismade in one piece with a bottom plate. The term “bottom plate” does notnecessarily mean that the bottom plate is plane. The bottom plate simplyforms a limitation of the oil-trapping chamber in addition to the outerwall. If the outer wall is made in one piece with the bottom plate, theresult is, in a manner of speaking, a “barrel” that surrounds the firstoil-trapping chamber. If the outer wall is made in one piece with thebottom plate, a smaller number of pieces must be handled duringdismounting of the refrigerant exchange arrangement, so that thehandling as a whole becomes simpler. Also the number of parts to besealed in relation to each other is smaller.

Preferably, a dividing wall between the first oil-trapping chamber andthe second oil-trapping chamber is made in one piece with the bottomplate. In connection with both the outer wall and the dividing wall, theterm “in one piece with” means that the walls are fixedly connected tothe bottom plate, that is, they cannot be detached from the bottom platewith simple means. Such a connection can be made by welding, soldering,gluing or the like. The corresponding parts can also grouted to eachother or be permanently connected to each other in other ways withoutthe use of auxiliary joining means. If the dividing wall between thefirst oil-trapping chamber and the second oil-trapping chamber is madein one piece with the bottom plate, this automatically results in asealing between the first oil-trapping chamber and the secondoil-trapping chamber at least in the area of the bottom plate. Thus, itcan be ensured in a simple manner that the oil introduced into therefrigerant in the compressor and the oil contained in the refrigerantin the air-conditioning system are kept separate from one another.

Preferably, a covering plate is arranged on the side of the firstoil-trapping chamber, which is opposite to the bottom plate, thedividing wall engaging said covering plate. This means that the coveringplate has a groove, into which the dividing wall projects. In a simplemanner, this provides a relatively good sealing between the firstoil-trapping chamber and the second oil-trapping chamber in the area ofthe covering plate. This sealing does not have to be completely tight. Alarge penetration of refrigerant gas or a refrigerant-oil mixture fromthe first oil-trapping chamber to the second oil-trapping chamber isavoided.

Preferably, the insert engages the covering plate. In this way it can beensured that the second oil-trapping chamber and the gas path leavingthe second oil-trapping chamber are separated from one another, namelyby the insert. Also here, a hermetic sealing is not necessarilyrequired, as oil and refrigerant can pass from one oil-trapping chamberto the other.

Preferably, the outer wall has a fixing flange in the area of thecovering plate. On the one side, the fixing flange strengthens the outerwall in the area, where a fixing to the covering plate is anticipated.On the other side, the fixing flange can also be used for locatingfixing means, such as screws or bolts.

Preferably, the outlet of the second oil-trapping chamber is connectedto a refrigerant collector. Expediently, this connection is made via acondenser and a filter drier. With the refrigerant collector, it ispossible to realise an intermittent operation, in which the refrigerantis treated by batch. A large refrigerant supply is then available in therefrigerant collector, which can be used again later to fill theair-conditioning system.

Preferably, a main pipe is connected via a first valve arrangement tothe first oil-trapping chamber and via a second valve arrangement to therefrigerant collector, the main pipe having at least one outerconnection. The outer connection serves the purpose of connecting theair-conditioning system (or another system), whose refrigerant has to beexchanged. The use of a main pipe simplifies the design. Via theindividual valve arrangements the part of the refrigerant exchangearrangement, which is required, can always be connected to thecorresponding air-conditioning system.

It is preferred that the main pipe is connected to a vacuum pump via athird valve arrangement. The vacuum pump generates a vacuum, with which,for example, the tightness of the air-conditioning system can be tested.If the vacuum remains for a certain period, this is a sign that theair-conditioning system is tight. If the pressure in the main pipeconnected to the air-conditioning system increases, this is a sign thatsomewhere a leakage exists.

It is also advantageous, if the main pipe is connected via a fourthvalve arrangement to a marking substance source. If a leakage hasoccurred, a marking substance can be taken from the marking substancesource and mixed with the refrigerant in the main pipe. This mixture isthen led through the air-conditioning system. The marking substance can,for example, be a colouring material. If this colouring materialpenetrates to the outside somewhere, a leakage has been discovered.

It is also advantageous, if the main pipe is connected via a fifth valvearrangement to an oil reservoir. The refrigerant can then be suppliedwith “fresh” oil, so that after servicing the air-conditioning system isready for work again.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described on the basis of a preferredembodiment in connection with the drawing, showing:

FIG. 1 is a schematic view of a refrigerant exchange arrangement,

FIG. 2 is a section through an oil-trapping unit,

FIG. 3 is a section of the view according to FIG. 2 with a non-sectionedinsert, and

FIG. 4 is a perspective view of the oil-trapping unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the form of a diagram, FIG. 1 shows a refrigerant exchangearrangement 1, by means of which a refrigerant can be taken from aschematically shown air-conditioning system 2, be purified and returnedinto the air-conditioning system 2 again.

The refrigerant exchange arrangement has a main pipe 3, which isconnected to two or more outer connections 4, 5. Via the outerconnections 4, 5 and valves 4 a, 5 a, which are allocated to these outerconnections 4, 5, the connection to the air-conditioning system 2 isrealised. Via a first valve arrangement 6, the main pipe 3 is connectedto an oil-trapping unit 7. The valve arrangement has an electricallyactivated valve 8, for example a solenoid valve, and a non-return valve9 opening in the direction of the oil-trapping unit 7.

The oil-trapping unit 7 has a first oil-trapping chamber 10 and a secondoil-trapping chamber 11. The first oil-trapping chamber 10 is connectedto the main pipe 3 via the first valve arrangement 6. A pipe 12 branchesoff from the first oil-trapping chamber 10 and leads via a filter drier13 to a compressor 14. From the compressor 14 a pipe 15 extends to theinlet of the second oil-trapping chamber 11. A pipe 16 that can beinterrupted or released by an electrically activated valve 17, branchesoff from the first oil-trapping chamber 10. The pipe 16 leads to a wasteoil collector 18.

Also from the second oil-trapping chamber 11 a pipe 19 branches off,which can be interrupted or released by an electrically activated valve20. The line 19 leads to the compressor 14, with the purpose of leadingoil back to here.

A gas path 21 leads out of the second oil-trapping chamber 11, said gaspath 21 extending through a schematically shown heat exchanger 22 andwhich can be interrupted by a non-return valve 23 opening in thedirection out of the second oil-trapping chamber 11. The gas path 21leads through a condenser 24 and and a filter drier 25 to a refrigerantcollector 26. The filter drier 25 can be combined with the filter drier13 to one component.

Via a second valve arrangement 27, which is formed by an electricallyactivated valve 28 and a non-return valve 29 opening in the direction ofthe main pipe 3, the refrigerant collector 26 is connected to the mainpipe 3.

Via a third valve arrangement 30, which can in fact be formed by onlyone electrically activated valve 31, the main pipe 3 is connected to avacuum pump 32.

Via a fourth valve arrangement 33, which again is formed by anelectrically activated valve 34 and a non-return valve 35 opening in thedirection of the main pipe, a marking substance source 36 is connectedto the main pipe 3.

An oil reservoir 37 is connected to the main pipe 3 via a fifth valvearrangement 38 comprising an electrically activated valve 39 and anon-return valve 40 opening in the direction of the main pipe 3. The oilreservoir 37 contains fresh oil, which can be added to the refrigerantsupplied to the air-conditioning system 2.

The oil-trapping unit 7 is shown as a section in FIG. 2.

The first oil-trapping chamber 10 is surrounded by an outer wall 41,which is made in one piece with a bottom plate 42. Also a dividing wall43 is made in one piece with the bottom plate 42, the dividing wall 43being located between the first oil-trapping chamber 10 and the secondoil-trapping chamber 11. Accordingly, the second oil-trapping chamber 11is located inside the first oil-trapping chamber 10.

Both oil-trapping chambers 10, 11 are closed by a covering plate 44 onthe side opposite the bottom plate 42. As can be seen from FIG. 4, thecovering plate 44 is mounted on a fixing flange 45 and connected to thefixing flange 45 by means of screws 46. Only one single sealing 47 isrequired between the covering plate 44 and the outer wall 41 in the areaof the fixing flange 45, in order to seal the first and the secondoil-trapping chambers 10, 11 towards the outside. A transition of oil orrefrigerant gas from one oil-trapping chamber into the other is notcritical. Merely the sealing towards the outside must be ensured.

In the second oil-trapping chamber 11 an insert 48 is arranged, whosecircumference bears on the dividing wall 43 from the inside. In itscircumference, the insert has a spirally shaped groove 49, which does,together with the dividing wall 43, limit a gas path 50, which leads outof the second oil-trapping chamber 11 and, together with the dividingwall 43, forms the heat exchanger 22 (FIG. 1).

Both the insert 48 and the dividing wall 43 are, as can be seen fromFIGS. 2 and 3, inserted in grooves 51, 52, which are formed in thecovering plate 44. Inserting the insert 48 and the dividing wall 43 inthese grooves 51, 52 does not necessarily provide an absolute tightnessbetween the various chambers, however, the tightness will be perfectlysufficient for the operation of the refrigerant exchange arrangement.

As can be seen from FIG. 4, practically all valve arrangements andvalves 4 a, 6, 27, 30, 33, 38 are arranged on the covering plate 44,except for the two valves 17, 20 which control the oil outlet from theoil-trapping chambers 10, 11. The valve 5 a cannot be seen here.

The refrigerant exchange arrangement 1 works as follows:

After connecting the refrigerant exchange arrangement 1 to theair-conditioning system 2, the two valves 4 a, 5 a open. Also the valve8 opens, so that a mixture of refrigerant and “old” oil reaches thefirst oil-trapping chamber 10. Here, oil and refrigerant are separatedfrom each other, in that the flow speed of the mixture is reduced somuch that the refrigerant can no longer hold the oil. In this case, theoil will lie on the bottom plate 42, and in the gravity direction therefrigerant will lie on top of the oil.

If now the first oil-trapping chamber 10 is heated, as explained below,this will cause the refrigerant to evaporate, while the oil remainsliquid, as it has a higher boiling point that is not reached by theheating. Via the pipe 12 and the filter drier 13, the refrigerant gasthen reaches the compressor 14. The filter drier 13 removes water fromthe refrigerant gas. When the total amount of refrigerant gas has leftthe first oil-trapping chamber 10, the valve 17 opens and the old oil isled to the oil collector 18.

The refrigerant gas is now compressed in the compressor 14, whereby itgets further heated. As during this compression process it ispractically unavoidable that oil will get into the refrigerant again,the compressed refrigerant gas will be led via the pipe 15 to the secondoil-trapping chamber 11. Here, the oil will be separated from therefrigerant gas. From the bottom of the second oil-trapping chamber 11it is led via the valve 20 back to the compressor 14.

The refrigerant that is now free of oil and under a certain pressure canbasically only escape from the second oil-trapping chamber 11 via thegas path 50, which is formed between the insert 48 and the dividing wall43. The hot refrigerant gas flowing through the gas path 50 transfersits heat via the dividing wall 43 to the first oil-trapping chamber 10,as mentioned above, in order to evaporate the refrigerant being in thefirst oil-trapping chamber 10.

The refrigerant, which still has an increased temperature after havingpassed the gas path 50, is cooled in the condenser and dried in thefilter drier 25. After that, it is led to the refrigerant collector 26.

As soon as the refrigerant has been removed from the air-conditioningsystem 2, the refrigerant exchange arrangement 1 can be operated asfollows:

If a replacement of some components of the air-conditioning system 2 isrequired, it can be made now.

All valve arrangements 6, 27, 30, 33, 38 are closed. Only the two valves4 a, 5 a, which connect the main pipe 3 to the air-conditioning system2, remain open.

Then, the valve 31 of the third valve arrangement 30 is opened, and thevacuum pump 32 is activated. The vacuum pump 32 generates a vacuum inthe air-conditioning system 2 of approximately 0.8 bar. Of course, alsoother vacuum values are possible. It is tested, if the vacuum can bemaintained after turning off the vacuum pump 32. If, after apredetermined test period, the vacuum has not changed by more than apredetermined value, it is assumed that the air-conditioning system 2 istight, and the refilling can start.

If the vacuum has subsided, this is a sign that the air-conditioningsystem 2 is not tight.

If it is assumed that a leakage exists, the fourth valve arrangement 33is opened. Due to the vacuum, a marking substance is sucked in from themarking substance source 36. When, then, the second valve arrangement 27is opened, the marking substance mixes with the refrigerant and flowsthrough the air-conditioning system 2. The marking substance willpenetrate through spots causing a leakage. Thus, these spots can beidentified and the leakages can be remedied.

When the leakages have been remedied or when from the beginning noleakages have existed, a vacuum is generated again, or the vacuum stillexists. In this case, the fifth valve arrangement 38 is opened, so thatnew oil from the oil reservoir 37 is sucked into the main pipe 3. When,then, the second valve arrangement 27 is opened, the new oil mixes withthe refrigerant and flows into the air-conditioning system 2.

Due to the simple design of the oil-trapping unit 7, the refrigerantexchange arrangement 1 is extremely easy to service. If, for servicepurposes, the oil-trapping unit 7 has to be dismounted, only four screwshave to be loosened. Then, the covering plate 44 can be removed, so thatthe two oil-trapping chambers 10, 11 are accessible. The insert 38 canbe removed from the second oil-trapping chamber 11 and be cleaned. Theremounting is made in the reverse order and is equally simple.

While the present invention has been illustrated and described withrespect to a particular embodiment thereof, it should be appreciated bythose of ordinary skill in the art that various modifications to thisinvention may be made without departing from the spirit and scope of thepresent invention.

1-15. (canceled)
 16. A refrigerant exchange arrangement with a firstoil-trapping chamber and a second oil-trapping chamber, the secondoil-trapping chamber being located inside the first oil-trappingchamber, wherein a gas path out of the second oil-trapping chamber islimited by a wall of the first oil-trapping chamber and that an insertis arranged in the second oil-trapping chamber, which limits the gaspath together with the wall of the first oil-trapping chamber.
 17. Therefrigerant exchange arrangement according to claim 16, wherein theoutside of the insert has at least one spirally shaped groove.
 18. Therefrigerant exchange arrangement according to claim 16, wherein theinsert is made of a plastic material.
 19. The refrigerant exchangearrangement according to claim 16, wherein at least one outer wall ofthe first oil-trapping chamber is made in one piece with a bottom plate.20. The refrigerant exchange arrangement according to claim 19, whereina dividing wall between the first oil-trapping chamber and the secondoil-trapping chamber is made in one piece with the bottom plate.
 21. Therefrigerant exchange arrangement according to claim 20, wherein acovering plate is arranged on the side of the first oil-trappingchamber, which is opposite to the bottom plate, the dividing wallengaging said covering plate.
 22. The refrigerant exchange arrangementaccording to claim 21, wherein the insert engages the covering plate.23. The refrigerant exchange arrangement according to claim 21, whereinthe outer wall has a fixing flange in the area of the covering plate.24. The refrigerant exchange arrangement according to claim 16, whereinthe outlet of the second oil-trapping chamber is connected to arefrigerant collector.
 25. The refrigerant exchange arrangementaccording to claim 24, wherein a main pipe is connected via a firstvalve arrangement to the first oil-trapping chamber and via a secondvalve arrangement to the refrigerant collector, the main pipe having atleast one outer connection.
 26. The refrigerant exchange arrangementaccording to claim 25, wherein the main pipe is connected to a vacuumpump via a third valve arrangement.
 27. The refrigerant exchangearrangement according to claim 25, wherein the main pipe is connectedvia a fourth valve arrangement to a marking substance source.
 28. Therefrigerant exchange arrangement according to claim 25, wherein the mainpipe is connected via a fifth valve arrangement to an oil reservoir.